I think Frank Thomas is in the same situation (as I recall).
What they are trying to achieve is to express that while Dickey got hurt often, it was only for very brief stretches. This is more realistic to me than the 15 game cliff below 600 PA.
Dickey '37 played in 140 of 154 games. I can understand if Strats wanted to adjust for catchers' fatigue and tweak his injury chance.
Same applies to : Mickey Tettleton "93 - 631 PA - 2 injury - played in 152 of 162 games. (RF primary position) Lance Parrish '84 - 619 PA - 2 injury - played in 147 of 162 games.
But then I don't understand: Bernito Santiago '91 - 603 PA - 1 injury -152 of 162 games. Butch Wynegar '77 - 600 PA - 1 injury - 144 of 162 games. (secondary position 3B).
Possible explanation: 1) Strong Strat-O-Matic bias toward the Twins and Padres 2) An "Oops Moment" at Strat-O-Matic.